I'm hesitant to speculate but just sharing -- an earlier version of this submersible was scrapped:
"OceanGate will take advantage of lessons learned during the construction of its carbon-hulled Titan submersible, which was originally built for Titanic journeys. Rush said tests that were conducted at the Deep Ocean Test Facility in Annapolis, Md., revealed that the Titan’s hull “showed signs of cyclic fatigue.” As a result, the hull’s depth rating was reduced to 3,000 meters.
David Pogue, who traveled to the Titanic with OceanGate last summer, has said that he was on the control ship when a previous sub was "lost for about 5 hours".
And the author is revealing this only now!?
That's not a great look, being witness to massive safety violations and keeping quiet about it until after it goes wrong.
Jesus. This sounds like this group is just taking billionaires' money while running a death trap. How the hell do you lose your sub for five hours? This should have stopped all trips until they fixed this problem through a combination of technical and procedural changes.
Their business model is to take wealthy explorers and also researchers, hoping that the explorers subsidise the researchers. So there is collateral damage.
I mean, if you accept that what you're doing is inherently unethical and immoral (I made a death trap but I'll let you pay to ride in it anyway instead of fixing it because you like danger and I like money!), then there's really no limit to the kind of terrible things you can put out into the world. But most of us would stop and reconsider what we're doing.
Communicating with submarines is actually a nightmare. The saltwater ruins most radio communications, so you have no chance to receive GPS signals, which are pretty weak even on the surface.
One thing the military does/did to communicate with subs is use low-bandwidth text-only very low frequency radio, but you need colossal transmitters and there's no way the mother ship carries one. Hydrophones are also an option, and IIRC NATO even has a working sound-based modem to transmit digital signals to subs, but not sure if that has spread in the civilian market.
Military submarines also have a towed communications buoy that they can use to communicate with satellites. But that thing is connected to the submersible via a cable.
The important issue with VLF radio in this case is that what we need is sub->ship communication. VLF relies on massive antenna, often ground based to (very slowly) send message to subs. My understanding is that for comms the other way, the sub needs to raise an antenna above the surface (then possibly doing laser comms to a satellite so that no radio emissions give away sub locations).
Because there is active search and rescue happening, a much lower tech solution is to use dye. But even that presumes a canister on the outside that can be activated from the inside and which will survive the depths of the dive. In retrospect perhaps something that does that automatically if not disarmed after a certain amount of time.
I'd think some kind of (1-way only, obviously), comms system could involve things attached to the exterior that are deployed by bluetooth or something, and float to the surface regularly.
e.g. every 2 hours, send up a transmitter that sends an "A-OK" on X Khz for at least Y minutes. If you get a bunch at once, or don't get any for a while, or get the "Something wrong" on Y Khz transmitter, you know something's gone awry.
If the sub had imploded, it is likely that the implosion may have been detected by various naval assets. I don't think that SOSUS is still active but there is very likely something similar with enough sensitivity to detect this somewhere in the ocean. The question would be if classification etc would allow speedy relay of that information to the search teams etc. Granted, not much to search for if there was an implosion.
I’m getting Virgin Galactic vibes. They’ve cut a lot of corners over there and they’re starting commercial flights this summer despite not having I’m convinced the most-safe aircraft. They’re out of money and they’re out of time. That’s what it always seems to come down to, not so much “time vs money” but “safety vs money”.
It's always safety vs. money. A risk-free submersible or spacecraft does not exist.
It's always possible to spend more money to further reduce the risks, but naturally with diminishing returns. At some point, you have to decide to accept (very small) risks in order to avoid (very large) additional costs.
People are perfectly happy to accept some risk. However you can’t expect normal people to take on extreme risk and expect a profitable long term business.
If the actual risk are close to BASE jumping then you’ve failed.
A big difference is things like BASE jumping / cave diving / mountain climbing require active participation and skill from the people experiencing them. I assume most fatalities in these sports are because of mistakes made by those participants (or health issues), not equipment failure by the companies facilitating them.
Adventure trips like Blue Origin, Virgin Galactic, and these OceanGate tours are passive experiences. Exhilarating, but you're not really expected to have any skill or do anything. I think a better analogy would be African Safaris - exotic, exclusive, and extremely expensive "adventures" for the wealthy. There's a powerful illusion of danger, but no one buying a package actually thinks there's a real chance they won't come home.
If these ultra-expensive, high-tech space and deep-sea adventures don't turn out to be as safe as, say, theme park rides, I wonder if there will be enough wealthy, risk-seeking adrenaline junkies to keep them in business.
I agree, you actively seek the activity and have often followed a long path of garnering the skills required to participate. It isn't surprising to a wingsuiter if their friend dies.
If a tour to the Titanic could be sold in a holiday package deal you're going to get people who don't understand the risks.
You do see it in holiday scuba diving destinations, where people are led to believe it is perfectly safe, and it's marketed to everyone. The reality of a dive is that you are just a couple of mistakes away from fatal consequences and the dive masters must know that as they strap a bottle onto a newbie and send 8 of them down at once.
There’s also business supporting people climbing Mount Everest, but their profits are severely limited by the number of people with means willing to take such risks.
It's a pretty robust and long-lasting industry, so the idea that their profits are "severely limited" doesn't pass the sniff test. They no doubt just increase their unit cost accordingly.
Anyway, although fewer than 1000 people summit Everest each year, 500 people per day reach Everest Base Camp, so there's plenty of room for profits.
Reaching Everest base camp is nowhere close to as risky as seriously trying to climb it. The record is 800 people per year actually reaching the summit and ~3,000 people making serious attempts.
That’s a tiny market, and yes companies do get involved but it’s not the sole source of income for any significant business.
It’s a matter of scale, right? 500/day sounds pretty low, if you’re trying to start a new airline or taxi company. But if I could sell 500 books per day that’s a huge slamdunk success.
Sure. A guided trek to Base Camp is, at a minimum, a few thousand dollars, and there's a good chance that's not the only tourist dollars you're spending while in Nepal.
Yea, but again a trip to base camp isn’t particularly dangerous.
If your business model is running a cruise ship where a few people take extreme risks and 98% are doing a normal holiday then sure that’s reasonable. Building a business on 3k customers/ year worldwide might survive but it’s lucky to make the same money as a single decent restaurant location.
Nepal introduced limits on the number of permits it will issue recently, because there’s more people who want to climb Everest than it can safely accomodate each year.
There are things that are even more dangerous than BASE jumping that people do for fun, like cave diving, but people do them. I never got the attraction of people to cave diving. All you have to do is kick up a little dirt, and you're pretty much dead.
Tourist Cave diver here, kicking up a little dirt happens on almost every dive, we train to deal with complete blackout scenarios, while sharing air, in restrictions but that rarely happens. Typical incidents relate to people doing a dive over their experience level or getting lost and running out of gas. Some cave systems are truly huge in scale and navigation can be difficult if you do a huge dive in one go. Personally i will only make 1 new navigation decision per dive so i can always visualize the cave. This goes out the window for those doing exploration type dives, then anything can happen.
Honest question, why do it? What’s the attraction of cave diving? Are underwater caves exciting enough that it’s worth the risk? Or is the risk itself the main thrill? Or is your perception that it’s not that risky?
I can understand the attraction of e.g. wingsuits, because the idea of flying like a bird is compelling, even if I would never risk my own life to do it. Although there’s definitely more than a few wingsuit jumpers who are doing it specifically to dice with Death e.g. proximity flying.
Personally I do it because it's the closest I will ever get to feeling like a space explorer. You are neutrally buoyant (weightless) completely relying on your equipment for survival and able to see places IN the earth very few people will ever experience, plus I love a challenge. When most people think of cave diving they imagine really small holes and limited visibility. Sure, that can be it if you want or you can visit places like this,
^ THAT is why I do it. Also I spent about 2 years in initial training and continue to train every time I dive. Our goal is to drive the risk to 0 which isn't reality but I feel less safe driving to some of the caves than I do diving them.
So the places we drive to are pretty remote and not in 'safe' spots. So I could sit at the hotel/resort and have no issues or get out on the road to the dive site. Every trip has had a story, not all good ones, but every dive has been worth it.
I am not a cave diver myself, but I do a lot of scuba diving and am friends with cave divers. Cave diving is one of the only remaining ways where an ordinary middle-class person can do original exploration without being part of some bigger organization. They can just get together with a few friends, fly to Mexico or wherever, and potentially go where no human has ever gone before.
Adrenaline is a powerful drug. And there's also a 100% focus (or very close to it), something that's really hard to achieve otherwise. Keeping yourself fit counts as well. I don't cave dive but I do ride MX which is also considered a risky sport. I'd say you'll hear similar answers from everyone dealing with risky sports/activities.
Surprisingly there are skilled but unfit cave divers. You are neutrally buoyant most of the time with little need for major physical exertion. I was a technical driver for over 6 years. The more efficient you become the less energy and air you use. I like to parachute and motorcycle too. I am a certified rope technician (SPRAT) and that takes the most physical exertion of the bunch for me, but that gets better with skill too. Gravity, the plane and the moto do most of the work for the others. That's why I go to a boxing gym for fitness among other activities.
It's not an adrenaline thing. Cave dives last for hours, not a few seconds like BASE jumping. If anything cave explorers do everything they can to minimize adrenaline production in order to hold their breathing rates down.
A generalization that I often hear for open water diving is that the drive to a dive place is more dangerous than diving itself, at least considering the time spent on the highway compared to the much shorter duration that is the dive.
That said, it does require a lot of training and certification, and people need to maintain that training and their gear. It not so much that kicking up a little dirt will kill you (it generally won't), but that a combination of complacency, stress and panic will kill you. In that it is again similar to driving in that in generally it is not the car or even the highway speeds that kills people, but rather complacency and a lack of attention to the road and traffic. Random tire explosion on the highway is a real risk, but even that is usually a lack of attention to maintenance.
Holy crap, I can't believe they're able to offer commercial BASE jumping to untrained customers. There's no way anyone would sell them liability insurance is there?
Insurance for the jumper seems to not be a problem. I couldn't easily find out about liability insurance for the operator, but I'd imagine that it's possible for the right price.
How many? No idea. But it's common to find it offered as a commercial activity — in a similar way to skydiving or other "extreme sports" — all over the world, as a quick web search would show you…
Can you show me a few? I did the quick web search as suggested, but cannot find the right keywords to find a lot.
What I did find is that BASE jumping is apparently often illegal (but definitely not everywhere per se), that everyone who did it can claim a “number”, and that 2000 numbers total have been claimed since 1981.
I’m not saying you’re wrong, I know next to nothing about BASE jumping. I’m curious what companies offer it commercially as an activity, and if that’s really widespread.
I just remember watching a documentary once, saying how crazy and uncommon it is.
Check my reply to your sibling comment for some links.
The only place I know of where it's specifically illegal is US national parks (only national parks — you're fine in Bureau of Land Management and Forest Service territories).
Of course, if you have to trespass to make the jump, that's itself illegal, but that has nothing to do with BASE jumping.
Yeah, I just don't get how "sitting in a 5 foot diameter tube for 24 hours looking through a tiny window" is exploring. You didn't make the project happen in any meaningful way - you're just a passenger. Seems like a pretty terrible way to pass the time, even when everything works as expected.
I can kind of see the appeal of Everest from a mountain climbing point of view, but I think I'd go and do one of the peaks without rush hour queues. So what if it's the 2nd/3rd/4th highest.
Running is a very high injury rate sport. Depending on what study you look at, novice runners has an accident rate of around 3.3 (that requires medical attention) per 100h of running. It is not without its own risk. Lower risk than climbing Everest or visiting Titanic, but still fairly high risk activity in a city environment with city traffic.
Swimming is a bit better if one want to a lower-risk sport.
Musculoskeletal overuse injuries requiring some level of medical attention are pretty common in every endurance sport, including swimming. But the number of people who actually die due to running accidents is miniscule. We usually have a few deaths every year in open water swimming and the swim portion of triathlon races due to medical issues like heart attacks and immersion pulmonary oedema.
It also isn't reasonable to expect "normal people" to be experts on every single thing so that they even realize they are taking an extreme risk in the first place.
A reminder to everyone that corners cut included having a control lever, which if pulled during re-entry, would immediately cause destruction of the craft, and for which there were no interlocks. That lever was pulled by the pilot and did indeed almost immediately cause the destruction of the ship.
Also, when Branson was aboard, they had a failure during launch that put them off-course and violated their flight plan (yes, they had a flight plan, and yes, this matters - the route is kept clear of everyone else.) They should have aborted the launch, but the Big Guy was on board, so full speed ahead.
I actually think those are somewhat forgivable/reasonable things for an experimental craft. My bigger concern is all of the current and ex-employees on Glassdoor talking about how morale is incredibly low and all the experienced folk were driven out and replaced by eager, young recent-grads willing to work 60+ hour weeks in the desert for what they seem to say is below-market pay. The only thing anyone really says about working for Virgin Galactic is that they work a schedule where everyone has every other Friday off. If that's the best thing you can say about your employer, you work in a sweatshop.
So you have all these I assume twenty-somethings working on VMS Eve, the prototype aircraft that takes the Spaceship craft to their launching point 30,000 feet up or whatever it is... Eve is basically two airplanes riveted together by their wings, and it's been why Virgin Galactic is years behind schedule on starting commercial operations. It's still probably going to be a maintenance nightmare, and if it decides to split in-air, they're certainly going bankrupt.
But Virgin Galactic isn't supposed to making an experimental craft, that was SpaceShipOne. They're supposed to be making the production version to carry passengers. You can't really have "ship blows up" levers once the public is on board.
Well they did address the “ship blows up” lever, which… it’s not fair to call it that, as though it were a self-destruct button, it’s a lever for controlling the orientation of the wings, since sometimes the ship is a glider and sometime’s it’s more like a rocket. If that lever is pulled too soon, it’s sort of like deploying extreme flaps on an airplane, it immediately and drastically changes the flight control surfaces and puts sudden force on the plane to go a different direction than it’s currently going.
It’s experimental in the same way commercial airplanes could be considered experimental until accidents went down to “basically zero”. Flying commercial was kind of risky until the ~70s.
Don’t forget Scaled Composites (Virgin Galactic’s partner) blowing up a pressure tank and killing three employees because they didn’t properly investigate nitrous oxide compatibility with composite materials and did a cold flow test on a hot day without any safety precautions.
According to David Pogue (journo who did a dive on this vessel last year), at least as of last year there was no beacon to transmit location. One would hope radio would be working, in that case.
The set of people that would enter an experimental sub to visit the titanic, and the ones that would do it with a craft that is bolted shut from the outside, is probably close to even.
And literally steered with a cheap game controller. There's a YouTube video from CBS of their reporter taking a trip on this thing. It's almost comical how cheap it seems.
What’s wrong with game controllers? They are built to be ergonomic and in use for extended periods of time. Also a lot of people are already familiar with how to use them.
Not saying we should replace every bespoke interface with a game controller, but using a game controller isn’t necessarily bad either.
Good point. Might be nice to have some redundancy if a game controller is used for a mission critical component, but apparently, the US military approves.
The key here to me is they use it for periscopes. An important function, to be sure, but no one is dying if the periscope controller fails. That isn't the same for the controller on the submarine where it controls lateral movement, which is critically important when going near a shipwreck or other hazards.
I saw a video where he said they used the controllers' built-in bluetooth. Bluetooth is anything but mission-critical. Imagine a disconnect when you're trying to decelerate.
I wonder if it at least had a radar reflector. This area of the Atlantic is notorious for fog, on account of the current which brought the iceberg there mixing with the 'Gulf Stream' (more formally known as the North Atlantic Drift at this latitude.)
You know what's the worst? Someone barging in into an established engineering domain and making spot judgements. This is simply incredible hubris that often is the hallmark of stupid but educated people.
If some brilliant improvement occurred to you in the first 5 seconds of hearing about some technical solution chances are this thought visited others in the past 100 years working on the problem for a living.
And if you hang around the problem just a wee longer and start actually thinking you quickly begin start to see the rationale why it was discarded. Like here, when there's a problem with air supply and the inhabitants are incapacitated, how do you open the bloody thing? But no, our hero never gets as far, he's already in a sister thread explaining how dumb it is seat belts get stuck when you pull them too fast or something.
It sounds like they could use some improvements, 5 people are probably dead now. Out of how many trips in that submersible? I don’t know, just wondering, but it can’t be that many. Certainly not comparable to commercial airlines. So that’s a pretty high failure rate. Being able to open the vessel from the inside in an emergency probably wouldn’t have saved them, it’s just the first thing that is too much of a red flag for me to personally ever step foot in that thing.
I also don’t even understand why that vessel needs to be manned at all. With today’s high def cameras and displays, including VR, they could outfit an unmanned vessel with high def cameras everywhere, a fiber optic tether to the surface to carry the high def signal (or even wireless to some degree if they could make that work), and the operator could sit in a control station either on the boat at the surface or streamed over the internet from home, controlling the vessel however he wants, with high def screens to simulate the viewing experience of being in the vessel. I’ll bet it would get you 99% of the way there without having to risk your life. It’s not like anyone is getting out of the thing to swim around the titanic in scuba gear anyway.
There are quite a few other manned submersibles designed for extreme depth that do allow for the hatch to be opened from the inside, in fact that's most of them. Alvin's design would be a nice starting point. It can be opened both from the outside and from the inside.
As for what the probable cause is: we don't know, we may never know. But with a device that was apparently designed by another party who declared it unfit for purpose anything goes.
I didn't interpret "traditional" as the rationale, but rather just pointing out that they're always done that way — I assume/hope for good reasons other than tradition.
I could see that as being the simplest/least failure prone way to design a closing mechanism that doesn’t need to resist the immense pressure to maintain integrity, but rather is held more forcefully to the hull as the pressure increases. Certainly you could design something like that that bolts from the inside instead, but perhaps the problem with that is that they cant exactly carry along with them various tools and equipment they might need in the event that there is difficulty reopening it.
Two hatches? One opens from the inside one opens from the outside? I'm sure there are other solutions.
But as somebody else already pointed out: even if you get out in the middle of the ocean you're in real trouble, which makes the hatch issue kind of moot.
Traditions emerge from "other reasons". There is probably not enough excess buoyancy to open the hatch without flooding, so without external support you're dead anyway.
No, the crew remains at 1 atm and the hull bears the pressure difference. Ocean pressure at the Titanic’s depth is over 400 atm (6000 psi!) but the oxygen level in normal air becomes toxic even at lower pressures. Technical divers use nitrox mixes, and the hyperbaric chamber record is 70 atm for a couple hours by breathing 0.5% oxygen and 99.5% hydrogen. (This mix can’t even explode, not enough oxidizer.)
Exactly. There are so many lessons learned already when designing a device like this there is no point in re-learning them the hard way, just adopt a tried and true design.
That's what they did? Alvin is an outlier; other bathyscaphes used the (tried-and-true) bolt-in method.
Assuming they're out there near the surface bouncing around in 6' waves and whitecaps, what they need isn't a door they can open and drown themselves with. Seems like what they need is a more effective location broadcast.
We don't actually know that they don't have good ways of being found. If they do, it makes it all the more likely that the sub is on the bottom :-(
I was imagining a round door in the middle of the hull, like a submarine hatch, but it looks like the entire front dome comes off and that’s the “hatch”. If so, can’t they just make the front a giant screw and add handles to both sides?
The dome shape is a structural necessity to withstand the pressure, like in a soda can. Else you would need more material, more material means more weight, more weight means more bouyancy required which again means more weight etc.
It's like designing a spacecraft but with different constraints.
But it's withstanding pressure(called external pressure, yesterday I learned), so can't they just have a clean, stepped flange to mate and to prevent slipping off, plus a simple lock to prevent unintended disengagement?
Then let me amend what I wrote: It's as difficult as designing a spacecraft, because you reach the limits of what materials that can be used can offer.
Well, once you are in space the forces are pretty tame until you get hit by something. But the ocean never rests from trying to kill you, even the smallest material defect can cause an implosion. Personally I think designing for a delta of 400 atmospheres in compression is much, much harder than for 1 atmosphere in tension.
I think it’s more the Apollo 1 door opening to the inside and secured by nonexplosive bolts, rather than the spuriously blown door on Liberty Bell 7.
FWIW, while NASA may had thrown him under the bus, his comrades in the astronaut corps believed him. Wally Schirra on Sigma 7, refused to blow the door until the capsule was on the Kearsarge. When he climbed out, he showed the bruise on his hand — the same bruise every one got when they pushed the escape button. The same bruise Grissom did not have.
That doesn't seem right, do you have any source? VLF wouldn't stand a chance of reaching that deep and ELF requires extremely large antenna to work. More likely they were using some form of underwater acoustic communication, sending and receiving data through sound instead of radio waves.
I don't have information about the type of communication link. I shouldn't have called it a radio link. Acoustic probably makes more sense. It was something very slow, so that sounds right.
In submersible tech, just beneath the surface is 0-30m depth basically (for salt water). Cellphones signals are about 2m max while higher frequencies (eg 2.4GHz) drop off exponentially so are <1m
Antennea can trivially extend over 30m, and can float on the surface. As a wire attached to an inflatable float, for either bidirectional communication or as a GPS beacon, or both, the complete solution could exist for less than $10k and less than 10 kilograms to solve this.
Why doesn't this exist for this craft that can only be openned from the outside??
There exists the ability to communicate from directly above, so why can't it also communicate (further) through open air while bobbing near the surface?
You seem to be under the impression that the people paying a quarter million dollars to get bolted shut in an experimental sub to go see the titanic are reasonable and people who would think of that. They aren't.
Could they just have some drills with diamond-tipped bits stored inside for emergency use? If needed, drill through the whole shell, stick an arm out and unbolt from the outside.
Or maybe a jackhammer to just hammer through whatever glass is there for observation purposes.
> Could they just have some drills with diamond-tipped bits stored inside for emergency use? If needed, drill through the whole shell, stick an arm out and unbolt from the outside.
A shaped charge might be a more sensible solution, but it's still within incredibly dangerous territory.
I think the point is to reduce cost and speed up operations by not having a tether. You can't do wireless video under thousands of feet of salt water. The options are AI or humans. There is a podcast and a news video linked here on HN.
If your design breaks at less than the target then you really have to question the logic of continuing with that design. Making it slightly bigger won't fix the inherent issue with the materials.
They're potentially opening themselves up to charges for killing these people. They knowingly or recklessly put them on a boat when it isn't capable of reaching the depth safely and now they are dead.
The fact they took it to some testing facility to test for cyclic fatigue shows that they understood that it was an unknown in the design, decided to test it at a facility designed for exactly that, it failed so they redesigned presumably with a design to mitigate the failures of design one. They probably took design two through the same testing process, and presumably it passed or they wouldn't have paying guests in it.
This sounds like the engineering process going right.
No coincidence the company is in Everett. LinkedIn shows lots of people overlap with Boeing. Also the CEO built his own composite airplane while an undergrad at Princeton.
the joke, you see, is that there must be something in the water or other environmental factor in the area that causes gross negligence toward commercial vessels
I don’t know about that. Charter commercial airline flights have worse safety records than other airlines. Often those involve pilots who are close to the business end of things and make poor choices because of it, even if it presents them some personal risk.
>They're potentially opening themselves up to charges for killing these people. They knowingly or recklessly put them on a boat when it isn't capable of reaching the depth safely and now they are dead.
Would the fact they almost certainly got the people to sign a fairly extensive release before they took them into international waters be relevant? I don't know how much of the "anything goes on the sea" thing is a myth.
“anything goes at sea” is definitely not right. I think international waters is pretty meaningless from an individual standpoint since the individual or company would always be under the jurisdiction of the ship’s registration as well as their own country (for lots of laws, such as you can’t sail off shore on a foreign ship and cheat on your taxes). International waters is mostly relevant for countries.
Yeah, destructive testing is still a must for process checking. Though non destructive methods for even composites keep getting better! Composites are very very hard to test though, and I think it's one of the biggest bottleneck to their usage.
(I work in NDT(non destructive testing) but on the software stack not the probes/scanners. So I'm not sure if my last point is still true these days! )
> Carbon seems to be the go-to material these days. It often seems to fail catastrophically in ways that, for example, steel does not.
Carbon fibre composites are also significantly lighter and more rigid than equivalent steel structures. As with all engineering it is about choosing materials with properties that suit your application.
I'm no expert, but I do know there's anything fundamentally flawed about polymer composites (including carbon fibre composites) in place of metals.
Composite properties can be fairly accurately measured and tested, just like any other material including plate steel or aluminium.
If a structural failure has occurred, it's related to a design, manufacture or maintenance issue. For example, not enough layers, or a weakness around a joint or fitting.
> Composite properties can be fairly accurately measured and tested, just like any other material including plate steel or aluminium
Metals are uniform and broadly predictable. Composites vary cure to cure. We simply don’t have the deep engineering tables that let you know how a material will behave without destructive testing.
Then there’s also the issue of minor failures cascading.
I’m by no means a structural engineer, but with bike parts — in steel or aluminum, if you get a tiny 1mm chip in the material, you can more-or-less just treat it as if the steel is 1mm thinner. With engineering tolerances it is irrelevant.
But in a carbon fiber, that 1mm chip could be totally unnoticed for months, while slowly causing an invisible hairline crack, until the entire component suddenly explodes with no warning.
Maybe someone can verify if that is possible at a larger scale, but I feel like it must be to some extent.. especially if there is an invisible manufacturing imperfection due to the higher precision required in carbon fiber
NB: Aluminium is rather notorious for its tendency to develop invisible hairline fractures which fail suddenly. Particularly around high-stress regions.
The BOAC Comet failures (cracks propagating from squared-off window corners) is a notorious example, with multiple total hull losses in flight.
I've experienced somewhat less significant failures of bicycle components (though they could easily have proved far worse). It's a good idea to replace components after a wreck or even hard-cornering of a crankset.
The cracks actually started on the top of the plane, at cutouts for radio antennas. The windows always had rounded corners (although they made them even rounder later, which may have led to the confusion.)
Didn't it take us thousands of years of working with metals (Bronze Age through Modern) to get them to the uniform quality we see today (at least speaking on a commoditized basis)?
I'm sure the story around composites will improve in due time.
Forging and heat treatment are processes to introduce uniformity of metallic grain structures. These have been perfected over hundreds of years.
I challenge you to find a single structural component in a safety-critical context which is made of cast metal.
These folks, among others, make a lot of them. You are also incorrect about forging being used to introduce uniformity into the grain, it is typically (though not always, as some forging operations may just be for establishing shape) to stretch the grains such that they are oriented along the load path, resulting in higher allowable stresses. Look up highly loaded aircraft parts like landing gear, they are typically forged to establish the grain direction and then machined to final dimension. Nothing stops you from heat treating metal after it has been cast, either. Some heat treatments are also expressly to produce nonuniform conditions in the metal, case hardening for example.
Composites can be tested. Not as easily as metals can be, and it involves a lot more software analysis and even AI, but it's still possible. I work on flaw detection/segmentation with ultrasounds -and I have not directly worked with metal scans so I can't exactly compare- but we can already get some pretty good results with the right probes and scanners. The other major issue is that NDT on composites needs more care and time from the inspectors on the ground, and might need a lot more organizational resources to track and make sense of the data.
But now that i think about it, I have no clue about performance or even feasibility of testing carbon composites. I'll have to ask around, but I'm pretty sure we have clients that use our hardware for Carbon! :)
Yes! Sorry if I wasn't clear enough. I meant that they use the devices because they are compliant and certified for carbon composites. I just wasn't sure since the devices are usually not for a single purpose so it's hard to keep track of all certified use cases from my PoV.
But sometimes they are! We have a few scanners specifically for pipelines and even robots for wind blades, yet even then the probe usually uses the same detection technology (ultrasounds, eddy currents, etc). The magic happens on the signal processing side when it comes to the difference between the scanners, and the trend is towards multipurpose all in ones. Our most recent industrial scanner has an FPGA that is explicitly there to allow for extensibility so that it fits most applications. FPGAs have been used quite often in the field but usually merely to implement some specific signal processing, not to be extensible!
I'm rambling here but my point is that some devices can be used for pretty much any application (the Omniscan for example), process specific devices are more for large scale industrial workflows! The probes can be the only thing you need to change to use the same scanner to do stuff as varied as hydrogen poisoning analysis on steel to composite flaw detection on windblades!
Super interesting work, thank you for the follow up. Some of my customers use stuff like this so it's nice to see someone from the supply side. It's interesting to think about the different kinds of defects. "Not like the rest" is a fairly easy kind of defect to detect, "Structurally different from the baseline" is a bit harder and a whole batch that is different in some important aspect is quite hard.
FPGAs are super powerful for applications like these, I see them used in plenty of sensors where flexibility and being future proof is a must so that you don't need to redesign the entire sensor for every variation on the theme.
Nomen est omen is a saying since the Roman times, and there are scientific studies that show names do have an effect on professions (eg there are more people named Art working with Art than youd statistically expect)
I think it's tiring when an industry that has no physical things to break, adopts a saying that flippantly implies that other industries are slow simply because they're not irresponsible enough. I've had quite enough broken things, thank you very much.
Learning to code is smart? Astronauts, doctors, lawyers, bankers and other gazillion jobs be damned. Coding is the dumbest job in my opinion compared to PM, or journalism.
Could you survive the Ukraine war coding?
Pressure hull made from titanium and carbon fiber, capable of diving to 4000m (13,000 ft).
I recall that one reason SpaceX switched from carbon fiber to stainless steel pressure vessels (fuel tanks) was the difficulty of detecting structural flaws.
Can any engineers comment on whether that task is easier for a vessel exposed to compression (under sea) as opposed to vacuum (space)?
How likely is a catastropic failure due to undetected flaws in carbon or composite (carbon + Ti) structures like these?
I've had some work in designing vessels to take external pressure.
It's fundamentally a nonlinear problem. A lot of new(and some not so new) engineers don't understand the process of solving it properly
For instance, euler buckling is the simple eigenvalue problem of solving a column in compression. But, it misses: initial defect because nothing is truly straight, material nonlinear effects if the part approaches yield strength, etc. I've seen it overestimate compressive capacity as much as 3-10 times depending on how geometry and material. You have to use more advanced techniques than just force over area.
Metallic vessels are difficult enough. You have to set up the problem properly and run nonlinear solves in the right way, and account for the right (or at least bound it conservatively) initial imperfections and analyze. And provide margin. Lots of compute time for a realistic analysis. And you probably still want to test. And you want to know your material very well, as the higher it's loaded, the more nonlinear that behavior could be too.
And that's with the simplicity of metal.
Composites are different. And that's not accounting for complexities of this problem. A lot of things get brittle at lower temperatures. Steel does, and I'm not sure about this particular material but at depth I would want to know specifics of temperatures and material behavior and select the right material for the job. Matrix and fibers themselves. Either failing would be fatal. I don't know enough here to say anything other than there are a lot of variables and I'm far enough away from the problem that it would take a lot of data to convince myself that I understood what could possibly happen.
I remember that being the mindset from industrial robotics: you're not modeling the device, you're modeling a device you can prove is weaker than the actual device.
Pity this isn't a top level comment, but you're spot on. Materials science for such designs is a really hard problem. And when you start cycling them the problems get harder still.
That’s sounds crazy complicated. In engineering is it like software design where you can get very far just being bad? Like do companies hire just crap engineers who don’t know all this stuff and call it a day? (Kind of like hiring offshore to build mvp for cheapiest crappiest quality possible)
Software failures don't usually visibly lose money, make a mess, or kill people. (Sometimes they do, see RISKS). So it's possible to have the usual sort of software project failure where something is 200% over budget and time, without anyone really waking up. But if a pressure vessel goes bang people tend to notice.
You can do that but you'll spend a lot of money breaking things. If you're in a non-safety critical field then that is a possibility. But, you really need good engineers, or to make them through these mistakes, to figure out what is really going wrong.
It is crazy complicated. In my experience, most companies have a few highly competent engineers who get funneled the work of lower level engineers with a review process. These engineers will also set up some domain-specific guardrails/guidelines that can help keep the lower level engineers from causing catastrophic issues.
Combine that with a healthy safety factor to cover the unknowable (internal material structure, etc) and you're generally safe.
There is a relative recent trend by fire fighters to replace old steel/aluminum cylinders with breathing gas to cylinders made out of carbon (300 bar). They are also used under water in diving.
The intend benefit is the reduced weight, but I wonder a bit how the failure mode might be a bit different from steel.
People deal with potential gas cylinder failure by occasionally testing them at higher than their usual pressure. You fill them with water and pressure to say 350 bar rather than 300. At least that's what they do with scuba tanks. Even if designed well they can be dropped, corroded etc.
The advantage of testing pressure vessels with water is that the failure mode is usually less bad than gas (because it doesn't expand through any breach like gas does).
Unfortunately a sub is the opposite of a pressure tank (the pressure is on the outside) so you need a pressure bottle bigger than the sub to test it in. I don't think these are common or easy to come by.
I've been in the reverse, an autoclave large enough to hold an entire spacecraft. That was already engineering on a scale that defied my imagination considerably, doing the same at the level where an entire sub could be pressurized to 400 atmospheres is engineering on a different plane. I don't think you could do this any cheaper/easier than just strapping it to a tether and dropping it overboard in a very deep part of the ocean, then winch it back in to see if it survived.
Gosh, that's one big autoclave. As you say, a sub tank would be even more of a monster bit of engineering. They do exist for more normal depths but I'm not sure if there are civilian / rentable sub test tanks for this kind of ultra deep stuff.
I guess in practice for something like the titanic sub, you could program it somehow to dive unmanned to some depth deeper than normal use and then resurface. Presumably with some radio beacon so you can find it when it does. Or a long cable connected to monitoring devices. If it didn't come back you'd have lost a sub but not lives.
Yes, that is what they do with steel and aluminum cylinders. After over pressuring them you measure how much the metal flex, and that way you get an indication of how much fatigue and thus risk there is with that cylinders.
I am unsure if they do that with carbon versions. Do they flex with over pressuring, and is that flexing indicative to failure? If they do fail, is it like an explosion where the whole thing just unwrap, or is it more like a leak?
Everest oxygen cylinders, made of titanium and kevlar usually sometimes get dropped off a cliff by accident, hit a rock and explode. Apparently they go off with quite a bang.
I'm not really an engineer (general hobbyist, former chemist) but I have built and worked with pressure and vacuum vessels.
Positive pressure (tank vs exterior) is much easier to deal with than negative pressure (vacuum vessel at 1 atm, or bathyscape with 1 atm inside and high pressure exterior). In positive pressure, your stress is mostly in the hoop mode, which is stable. This is why aluminum cans can be so thin. In negative pressure vessels, you have a buckling mode, which is inherently unstable. As soon as it goes, it goes all at once.
I've had a 2L glass vacuum flask implode on me. There is no warning. All it takes is a tiny defect, and once you hit a certain pressure delta, kaboom. Composite is similar in that it's mostly brittle failure vs ductile. I've also imploded a 55 gallon steel vessel. That goes a lot more gradually (though still fast) - maybe enough to detect and abort the trip.
The other main advantage of steel vs composite is you can inspect with X-ray imaging to find defects.
In college, a popular showoff trick was to set an empty beer can on the floor. Then balance on it with one foot. If your balance was good and well centered, the can would not collapse. Then, for extra credit, slowly reach down and just tap the side of the can with a finger tip. The can would instantly crush to a disk. Extra karma points for crushing it into a perfect circle, rather than an oval.
It would collapse so fast it was nigh imperceptible.
Bill Hammond, the Engineer Guy on youtube, has a video on the design and engineering of the aluminum can with a brief clip of someone standing on a can (around the 7-8 minute mark).
Also space pressure difference is much less. A fuel tank might have just a few atmospheres inside, and of course a human pressure vessel will have a bit under 1 atmosphere inside, compared to the outside which is at ~0 atm.
At 4000m, the outside pressure is _400_ atmospheres compared to just one inside. It's way, way harder.
> A fuel tank might have just a few atmospheres inside
Not quite. The composite overwrapped pressure vessels (COPV) we are talking about are easily pressurised up to 5000 psi [1]. That is about 340 atm. They use these tanks to contain helium as a pressurant, and nitrogen for the life support systems.
Elon talked in a tweet about higher numbers. 6k psi and 10k psi in this tweet[2] but it is unclear if he is talking about design works or actual pressures they have flown.
All in all you are right that the difference between the people tank and space is only 1 atm, but that is not where the challenge is in terms of space exploration and pressure vessels.
No, they don't, not any more. That was decades ago.
High-end and racing road bike tires now are in the 40-75 psi range, and they're much wider than they used to be. They finally figured out that skinny, high-pressure tires are not only very uncomfortable, they're slower too.
Holy crap. The speed is so high you can't even catch the intermediary phases on that video. And the casual distortion of the carrying frame is such that the rear wheels of the car no longer contact the rails.
Until recently at least, there had been more people on the moon than the bottom of the Mariana Trench. (There’s been a flurry of descents in the last few years, so by now the stats might have flipped.)
If space is easier than the deep ocean, how is it that the Trieste (the submersible that explored the Challenger Deep) was built in a year on a budget of millions by a single shipyard, while it took massive, multi-year, multi-billion dollar, national efforts to go to space?
The tyranny of the rocket equation. Or simply put you don't have to carry fuel to carry fuel to carry fuel to get you to the bottom of the ocean. Simply carrying some ballast will do just fine.
The pressure hull isn't the major engineering challenge in getting to space.
Because getting into the ocean just requires some ballast. You can jump overboard any ship at any time in a diving bell and see how far you make it. Or not. But going to orbital velocity is another matter entirely. But once you are in space vs once you are in the deep ocean the environment will try to kill you in entirely different ways and in that sense space is easier than the deep ocean. Some parts of earth are off limits with present day technology and the Titanic is roughly on the border of what you can do with some degree of reliability. And probably less reliability than was forecast. With space, once you are out there given enough fuel the solar system is your for the taking. Until you dive down in another gravity well.
Difference in difficulty of getting there. The pressure vessel for space could be far simpler than going underwater. But it is way harder to get to the point where you’d need a space pressure vessel in the first place
A series with teleporters, time travel, warp drive, artificial gravity, deflector shields, all manner of ESP-type woo... and submerging a spacecraft is what ruins it for you?
Yes. It breaks the established rules of the world.
I also have problems with the Enterprise being built in a canyon in… checks notes Iowa?!? Also, I hate the transgalactic teleporter JJ has Kahn use to to escape, and pretty much the entire plot of JJ’s Star Trek 2. I already saw that movie, done better. It was called Star Trek II.
At risk of defending JJ Abrams, hadn't Leonard Nimoy already submerged the Enterprise (NCC-1701-A) back in 1986 when he directed Star Trek IV?
That said, I've long agreed with others here who take issue with the idea of landing star ships that are supposedly so large and structurally precarious they more or less must be built in space. On reentry the dynamic stresses on the hulls of those ships would be insane to the point of absurdity.
>At risk of defending JJ Abrams, hadn't Leonard Nimoy already submerged the Enterprise (NCC-1701-A) back in 1986 when he directed Star Trek IV?
Huh? No, where did you get that crazy idea?
There was no Enterprise in the movie, because it was destroyed in the previous movie. The crew used a Klingon bird of prey to go back in time, and they didn't go underwater, they built a tank inside the ship and beamed some whales (and water) into it.
>On reentry the dynamic stresses on the hulls of those ships would be insane to the point of absurdity.
And how does that compare to the stresses on ships that can (in most sci-fi) accelerate to a significant fraction of lightspeed very quickly, or perform extreme maneuvers during space battles?
Even in Star Trek, they recognized that inertia and structural forces would be a big problem with the plot, so they "invented" the "inertial dampers" and the "SIF": structural integrity field, which somehow manages to make the ship strong enough to handle crazy forces well beyond the strengths of the materials it's made from.
Voyager I’ll allow since it’s small and pointy, and came with landing gears. The Enterprise is too big. You only get to “hot drop” that saucer section once. (Galaxy class only. Any other saucer sep is apocryphal.)
I hate that Rogue One had Star Destroyers hovering in atmosphere. That’s just dumb, and destroyed the lore about Victory versus Imperial class Star Destroyers.
I loved Rogue One for all the EU hardware they used. And the new TIEs they introduced were cool, too, the TIE Striker is the new canon version of the Scimitar in my head. If they had parked a VSD over the city so, that would have been the crown!
Yes, but not only, there is number of pressurizing/de-pressurizing cycles to be taken into account (that lead to fatigue), this is more known for hulls of (pressurized) planes.
They esperience at least two full cycles per flight, a submarine has as well at least two of them, but with much larger pressure values, for each immersion.
AFAICT, steel is still preferred to titanium because (besides the costs) this latter tends to become (after a certain number of cycles) more brittle than the particular kind of steel used in submarines.
Carbon fibers are strong in tension. That's why it is good for pressure vessels that are trying explode. Your wrap the fibers on the outside of the pressure boundary. Same concept that you can only pull on a rope, not push it. I'd be interested to see how they are using carbon fibers in compressive applications like deep sea vessels. Is that more of a marketing thing? "Carbon fiber" sounds sexy, so we'll advertise that we're using it, but it is really for non-load bearing applications?
Carbon fiber hulls are used extensively in remotely-operated vehicles, Edit: (I was mistaken there, those are metal hulls - but there is a plethora of research RVs with glass fiber hulls) e.g. the ones that the Navy uses (torpedo shaped) but they fail after a while. [0]
The glass fiber design is based on the Deepflight Challenger design which Virgin wanted to use but deemed only safe enough for one dive:
"Based on testing at high pressure, the DeepFlight Challenger was determined to be suitable only for a single dive, not the repeated uses that had been planned as part of Virgin Oceanic service." [1]
The CBS news article referenced in another reply says the body of the sub is 5-inch thick carbon fiber with titanium used in the rounded ends. I am surprised it’s just carbon fiber in the body.
...still not seeing what the carbon fiber is buying here, other than historical reasons / "that's how we do composite pressure vessels". Maybe it adds some slight rigidity when it is being raised up out of the water?
From the linked article: "OceanGate CEO Stockton Rush says the company had been evaluating the potential of using a carbon fiber composite hull since 2010, primarily because it permits creation of a pressure vessel that is naturally buoyant and, therefore, would enable OceanGate to forgo the use — and the significant expense — of syntactic foam on its exterior."
My first thought was that expanding foam from the hardware store is very cheap, but obviously that sort of foam would be crushed by the water pressure.
> Syntactic foams are composite materials synthesized by filling a metal, polymer,[1] cementitious or ceramic matrix with hollow spheres called microballoons[2] or cenospheres or non-hollow spheres (e.g. perlite) as aggregates.[3] In this context, "syntactic" means "put together." [...] The compressive properties of syntactic foams, in most cases, strongly depend on the properties of microballoons.
Not very because air-entrained concrete has very little resistance to crumbling and doesn't handle tensile stress well (which you could fix by adding fibers or some other element that handles tension better, hence reinforced concrete). It has plenty of applications under normal atmospheric conditions but for submersibles you will want something with entirely different properties.
clowns. the pressure hull of a deep-sea submersible is not the place to go looking for cost savings, especially when the target clientele is cost-insensitive billionaires.
The failure mode for a member in compression is buckling, which is resisted by stiffness, not strength.
It's also a lot easier to make a huge thick tube out of composites than out of titanium. That's why only the spherical ends are titanium, and the middle tube part is CF.
>The failure mode for a member in compression is buckling, which is resisted by stiffness
Hmm, this is probably the right answer. When things start to buckle, you'd be putting part of the surface in tension, which would be resisted by the fiber. I would definitely be very interested to see the plots of strain gauges embedded throughout the thickness of the wall as it goes to depth (in all three axes, hoop, radial, and axial). My intuition completely fails here. Good thing I'm not making submersible vehicles.
Once buckling occurs, it hardly matters what's in compression and what's in tension: the applied force has a tremendous mechanical advantage over the material strength resisting it once the stiffness fails to prevent it from crossing a threshold.
Secondly, CF does substantially improve compressive strength over neat resin, which would fail in shear.
The fibers individually may not withstand compression, but embedding them in the epoxy resin prevents them from buckling and the composite material exhibits substantially improved performance over either base material.
The exception is tensile stress that causes delamination, for which there is no benefit over the neat resin.
It would be a good thing if the people who did make this contraption also didn't make submersible vessels based on the bits and pieces that have made it into the news so far. This sounded like an accident waiting to happen. At those pressures if something goes wrong it will crumple like a tin can and having the hatch sealed from the outside means that even if they didn't die at depth they may not have a way out if their comms have failed. The whole thing strikes me as beyond irresponsible. I wonder if the people that built the sub would take it to depth.
In what scenario would not being sealed from the outside make a positive difference? If they managed to surface, how would being able to "get out" in the middle of the ocean be helpful? If they didn't manage to surface, under what circumstances would have opening the hatch helped?
True, although fortunately the air supply is meant to last for 4 days. As a passenger I would probably be more alarmed about the apparent absence of some kind of distress beacon than the inability to open the hatch without help.
Well, something went wrong and one of the things that could go wrong is the air supply. I wouldn't be a passenger for any amount of money, these are experimental tools, not joy rides.
There was a distress beacon… it’s called a transponder. It is in a separate pressure chamber controlled by a separate battery. It is a completely separate and isolated system. It failed at the same time as regular comms leading some to conclude the vessel was gone. Kaput. Is no more.
I think part of the issue there is designing a hatch that can be opened on the surface to exchange air without immediately swamping the sub in the sea chop. Alvin sank very fast when it was accidentally dropped into the water with the hatch open.
They copied the glass fiber + titanium rings idea from the Deepflight Challenger that Virgin wanted to dive with. [0]
Virgin deemed the design not safe enough for more than a single dive and quietly scrapped the diving events: "Based on testing at high pressure, the DeepFlight Challenger was determined to be suitable only for a single dive, not the repeated uses that had been planned as part of Virgin Oceanic service." [1]
Poor design choice. Too many materials expanding and contracting at different rates leads to friction stress and ultimate material failure. Maybe not at first, but over repeated compression and expansion cycles.
It seems like the epoxy in this composite structure is sustaining all of the compressive loads. The carbon fiber would seem to be just along for the ride, so to speak, since fibers are only useful in tension. Am I missing something?
Wouldn't this be a bit like reinforced concrete? In practice there are not just pure compressive loads, but flexing and shearing that put some areas under tension, so the embedded reinforcements fight that and help keep the bulk material in the right places.
Also, think of the bill of a toucan or fiberglass surf board. A lot of rigidity comes from the tensile strength of the skin wrapped around an enclosed volume of relatively weak stuff that mostly keeps the skin in the right configuration.
Here "in practice" actually means "in sheets." If you have a flat sheet of concrete / carbon fiber composite supported at both ends, and then you apply a downward force in the middle, the top of the sheet will be in compression while the bottom of the sheet will be under tension.
In a negative pressure vessel that's a cylindrical shell, all of the force is being applied uniformly inward from the outside surface of the cylinder, so every part of every fiber will be in compression. There's no part of the structure that outside pressure would deform in a direction that would stretch the fibers -- you would need to have greater pressure on the inside for that to happen, and in that case, the fibers would again all be in tension.
One failure mode to consider is shear failure (i.e. if the changes in circumference due to compression on the outside vs. the inside of the hull are too different, resin between layers could start to fail.
The other would be micro-buckling of tiny sections of fiber in areas where the resin has already failed, or isn't as strong, or in layup defects.
If either of these cause enough deviation from the nominal structure shape to allow buckling to start, the hull will fail catastrophically.
> Also, think of the bill of a toucan or fiberglass surf board. A lot of rigidity comes from the tensile strength of the skin wrapped around an enclosed volume of relatively weak stuff that mostly keeps the skin in the right configuration.
It is like this, but as another comment [1] pointed out, in the case of a negative pressure vessel, the configuration is unstable -- If you develop just one defect, the entire thing implodes. You might be able to buy yourself a little more headroom with something like pre-stressed / post-tensioned concrete (not sure if there's a practical equivalent for carbon composites), but this is a pretty extreme negative pressure vessel...
>Also, think of the bill of a toucan or fiberglass surf board. A lot of rigidity comes from the tensile strength of the skin wrapped around an enclosed volume of relatively weak stuff that mostly keeps the skin in the right configuration.
So in other words carbon fibers are a bit elongated (or straindd) in CFRP? What increases shear strength of the composite but could weaken its compressive strength?
Interesting.
There must be interior bulkheads(walls), your idea of shear could very well happen where the bulkheads prevent tension of the inside surface.
This makes me think, why didn’t they build in composite reinforced bulkheads every 12 inches or so. That definitely would have had substantial impact on compressing the cf hull and preventing delamination. So obvious.
One disadvantage of Carbon fiber/composite material is that the surface can get electrically charged and cause an arc. It could be that inside the Titan there was an electric short circuit (DC short circuit can produce enough energy) and a Flash fire originated in which flames engulfed the entire capsule rapidly, consumed all the oxygen, decapacitated all the crew. due to the heat generated and the negative pressure created inside, resulted in an implosion of the vessel.
It is basically a composite material. Carbon fibers bonded with resin compound.
The fibers need resin to keep them all together and create a non pours barrier for the fluid contained. The fibers are in tension under the application of internal radial pressure. without the fibers, the resin, having brittle properties cannot handles the tensile hoop stress.
>The most significant innovation is the proprietary real-time hull health monitoring (RTM) system. [...] provides early warning detection for the pilot with enough time to arrest the descent and safely return to surface.
I imagine the search and rescue effort have checked the seismograph/ocean sounds/other networks, AIUI an implosion at depth makes quite a bang, so not detecting one would be a positive.
I too am interested in this question, may I piggyback and add a question about whether the basic capsule shape is as efficient in negative pressure as it is in positive pressure
There's a formula for designing the strain on pressurized vessels especially when the
strength characteristics of the material used is known
The thicker the material used for the vessel the more pressure It will take That's obvious & simple so far
They used carbon fiber and titanium fiber probably interwoven and then glued there is a procedure for this
There's also a nominal, working, and burst value after these vessels are manufactured. Basically established by testing
There was no testing on this vehicle non-destructive or destructive That was bypassed
Also I believed it was planned to be a 7-in thick vessel this one for some reason was 5-in thick
Two of the employees from oceangate were sued and dismissed for making issues of the safety of this vessel particularly about the thickness and particularly about the gluing process
(That isn't even that strange in any industry where there is engineers)
Especially in R&D situation like this
So you have a material which the mechanics of that material are not fully understood
Being used to manufacture a vessel that's going to withstand unimaginable pressures because of its size every square inch of that vehicle had 4,000 per square inch on it
It's of a certain configuration (shape)
Needs to be tested
The other thing I would bring up is I wonder if the gasket failed they're almost at full depth
Maybe they didn't change the gasket or they change the gasket and it was of a different physical characteristics
The gasket is used on the hatch which was bolted shut
The gasket surface design is very critical at that pressure also
I think you can rule out fatigue because carbon fiber and titanium for that matter have really high fatigue resistance
My background is in aerospace and while I’m not an expert on COPVs, I’m familiar with their design. Carbon fiber overwrap is really good for internal pressure applications or in other words, the typical pressure vessel due to carbon fiber’s very high tensile strength. Think of those videos where folks put rubber bands on watermelons to make them explode; the concept is similar to a COPV in that the rubber bands (carbon fiber) “compress” the watermelon (pressure vessel) to “contain” the pressure. COPVs can take high internal pressures of 6000 PSI (which is the same internal pressure of the ISS NORS tank used to recharge oxygen and nitrogen on the ISS and coincidentally is the same *external* pressure experienced at the depths of the Titanic. (Some helium bottles have higher internal pressure). While in aerospace applications there are some load cases where the COPV has an external pressure load on them like a helium bottle stored in a propellant tank on a SpaceX Falcon 9, those pressures are nowhere near deep sea pressures.
The reason why I don’t think COPVs are a good design for an external pressure application is the load direction; carbon fiber tow doesn’t really do well maintaining an external load. Think back to the watermelon example; apply an increased external pressure and the rubber bands really don’t help with withstanding that increased pressure.
Carbon fiber itself is very difficult to verify that you have the correct properties once they're wound onto the tank. The properties are anisotropic meaning depending on the direction of the fiber you’re gonna get different mechanical properties. Defects like delamination (when a wind unwraps) or voids between the tank wall and fiber are common if you don’t have a qualified winding operation and really really good procedures. In short, while not needing software, repeatability in manufacturing a COPV is incredibly difficult. Part of the reason SpaceX switched to metal tanks is that the mechanical properties of stainless actually increase in a cryogenic environment so there’s an added benefit.
In 2016, SpaceX’s Falcon 9 carrying AMOS-6 exploded during a routine static fire due to a buckled liner of a COPV on the 2nd stage LOX tank. The liner buckled which created a void between the liner and the fiber overwrap which then developed solid oxygen (or an ingress of LOX) that initiated an explosion due to friction. Falcon 9 had been flying for 6 years at that point so I’d consider that a pretty mature or at least an “operational” vehicle so for it to explode on the pad like that is how tricky COPVs can be.
I think Titan imploded killing the crews instantly. This would explain sudden lost of contact and subsequently unable to find them. Those fiber has been confirmed to buckle from cyclic pressure. The take away from this incident is OceanGate should have pursue Edison manual ways of repetitive testing. It would be very expensive but the knowledge gather from those test will enhance material science of carbon fiber use in that kind of scenrios and design specs. Instead they prefer to fire the engineer whistleblower who try to save them. Such irony.
For those looking for more detail on the engineering of the vessel, refer to this brief walk-through from Rush himself filmed by a Mexican travel blogger back in July of 2021:
The failure of the carbon fiber is a repeated theory of what could have happened to OceanGate Titan. Is there any information on the difference expansion and contraction of titanium versus carbon fiber. The seal between the end-caps and the carbon fiber hull would have to be very flexible and would be susceptible to failure. Any thoughts on the seals being the failure? I'm a US submarine veteran.
Given that it's named the "Titan" and described as "the world's only privately owned manned-submersible capable of reaching Titanic depths of 4000 meters" [1] I suspect this was designed with the Titanic in mind.
You would hope that would include a substantial safety margin.
I wonder if it has an adaptive pressurisation system, similar to airplanes but in the opposite direction, where the internal pressure is allowed to increase up to a certain point as it descends to reduce the pressure differential.
Skimming the website, I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost, the weights drop off and the submersible floats up to the surface again?
And 96 hours of life support sounds good, but unless there is another submersible nearby that can dive down, find them AND attach a line, the number of hours of life support will be irrelevant. Of course if the pressure hull has failed catastrophically it will have been over mercifully quickly. Anyone know if deep-diving submersibles are required to carry black-boxes like aircraft?
A location pinger would be a no brainer but like you say, it only helps if there's another sub with a grapple in range, in time.
I understand why oceanographers /might/ want to do this, but not in person when ROV tech is so good now, for biology and tourism. There are so many things that can happen to fragile humans in that complex machine: drowning, freezing, asphyxiating, crushing, oxygen narcosis, nitrogen narcosis, co2 poisoning, and the plain old bends.
So why do people risk all that, and pay 125k to do it? Why the titanic obsession? It's only the fourth worst maritime disaster (Doña Paz in 1987 had 4k deaths) and so what if someone made a movie about one.
Not that it appeals to me, but I would guess that the appeal of the Titanic lies in it being the canonical 'technological hubris' story and a contender in the 'if only...' category.
It is one thing to do it in person and an other to see it on a screen. As a diver I can fully understand why they want to go down there, for the same reason astronauts want to visit space instead of just sending up a satellite with a video camera.
That said, yes, titanic might not have been my choice personally. It has a sister ship that lies at a more reasonable depth of ~100 meters, so divers can actually be in the water and explore the inside. It is also fairly intact in contrast to titanic which is broken in half with the stern being mostly destroyed.
This video strikes me like a TV clip from a more civilised era or something. It's calm, there's no annoying music, the initial presenter didn't say anything too clickbaity. It's oddly calming.
@2:40
reading contract: “[…] an experimental submersible vessel that has not been approved or certified by any regulatory body and could result in physical injury, disability, emotional trauma, or death. Where do I sign?”
“Pretty good controller, fits in hand comfortably and is compatible with anything I throw at it in a Debian linux environment. The conductive pads are extremely low quality though as I've had to replace them 3 times in the 2 years Ive been using it. For a Logitech product I expect better build quality and reasonably easier to find replacement parts but not true for this product.
Last night I had the left directional button go out on me and without parts on hand I ended up breaking down an old wired controller I had laying around. The IZDTech controller i used for parts is over 5 years old and the conductive pads are still in good shape. With a little modification I was able to get them to sit 'okay' on the buttons. Until i can find the appropriate conductive pads this will have to do.”
Good lord, at least use an Xbox controller. They are supported pretty much everywhere and are very durable. The US Navy uses them because they are durable and because new recruits are already intimately familiar with them.
I mean that’s good lateral thinking but the issue is not that one particular button will go out but that any button or buttons could, and at any time, and it would probably be the most-used buttons since it was wear-based failure.
They also briefly showed a single button on the wall that it was implied functioned like an elevator button.
There were a lot of ways it looked like things could trivially go wrong, once you got a feel for how it was built.
Ok that’s absolutely bizarre!
That and the rest of the interior made from alibaba products that should have been military grade.
Can anyone even try to explain this choice? Even a hobbyist would curate the inside with top of the line products and aesthetics - this dude this dude has just jerry rigged some cheap chinese crap - what the actual hell?
It is a submarine that carries people to depth. I don’t think it should have consumer-grade lighting designed for an RV that has windows and an exit that is always possible to use.
It should not have a low-cost consumer-grade controller.
The CEO should not be bragging about the fact that it does, on camera. It demonstrates an incredible lack of experience and/or mental disconnect. All of this would be fine if it were a boat in an amusement park 1 meter pond or something, but it is in the open ocean at depth. It was a matter of time before people died.
> I assume this submersible is using electromagnetically attached drop-weights so that if anything goes wrong and power is lost
I don't think they have any "drop-weights" which would make them positively buoyant. If I'm reading the spec-sheet correctly, the submersible itself weights ~1500lbs. Subs have ballast tanks which they pump with air and force out water to make themselves positively buoyant. But if something goes wrong with the mechanism to fill the ballast tanks, I'm guessing they'd just be stuck at depth.
(disclaimer, I am far from an expert at this - I just have a cursory understanding of Boyle's law)
There are typically compressed air cylinders that can expel the water in case of emergency. At least on military submarines that go down to 300m, it may not work 4km down where the pressure is ridiculous.
Standard scuba cylinders are typically pressurised to around 230 bar, with a small proportion taking 300 bar as their standard working pressure (with margin for over-pressure).
It's not too much of a leap from there to the 380 bar pressure at Titanic's depth.
Indeed, this company[1] seems to sell COPV's that are rated for 414 bar, so my assumptions were wrong in this case.
As such, I will revise my theory, and posit that the actual issue with this strategy at Titanic depths is keeping the water out of the ballast tanks once you've evacuated them. This seems plausible given that the hatch must be bolted on from the outside. If they had a method to keep 382 bar of water dynamically out of the ballast tanks, presumably they could use that same method to have a hatch that can be opened without manual screwing.
> If they had a method to keep 382 bar of water dynamically out of the ballast tanks
By filling the ballast tanks with 382 bar of air.
The human-interior of the sub is maintained at 1 bar to avoid compression demands (hyperoxic seizure triggers at approx 7.6 bar when breathing atmospheric gases; HPNS (High Pressure Nervous Syndrome) is common after 16 bar on a helium-oxygen mix), and decompression requirements.
Equalizing the inside-outside pressures would help a lot with the composite materials, and somewhat less so with the fleshy meat bags inside.
I think you may have led me astray with that first comment, and that my intuition was probably correct. How exactly does one purge the ballast tank with the air tank? Would you not actually need an air tank that has (at least) double the pressure of the outside water? Then to clear the ballast tank you would open the air tank, the higher pressure air would then force out the lower pressure water (this is clearly why it can't be the same pressure as implied in your first comment), and then when you're done you have two tanks (your air and ballast tanks) both at 380 bar, assuming they are both the same volume.
In that case you'd actually need a PV rated for 740 bar, which seems outside our current materials science abilities. In fact (and I'm still mostly just spitballing here, not actually doing any math), I assume you actually need a purge tank with a pressure much greater than 2x, otherwise you're just cancelling out your ballast with your air tank, right?
That would track with using this system in submersibles that are operating at ~300m and not for things like this which are trying to operate at 4000m. At 300m you could have a 400 bar COPV for emergency purging that is only 7.5% the size of the ballast tanks, which sounds practical.
I've read that many military submarines have an "I've sunk" buoy. It detaches from the boat under commanded deployment, after some elapsed time without reset, or when external pressure rises way beyond crush depth. They're positively buoyant. They have radio beacons to report the event when they rise to the surface.
> As it may be difficult to manually release the buoy, or the compartment where the buoy controls are located may have been flooded, the buoys were arranged with automatic releases, in the event of a fire or internal flooding. Such automatic sensors proved unreliable and buoys were sometimes released unexpectedly. Accidental release of a buoy would have been a hazard during wartime operations, or even during exercises. There is some indication that unreliable buoys were welded into place. This may have been a factor in incidents such as the Kursk sinking, where the buoy was not released and it was difficult to locate the wreck.
I see so many parallels to bad devops patterns I’ve seen. You build your incident response protocols around a metric alarm (bouy being released). However the alarm is noisy so people either ignore the alarm or suppress it (welding the bouy in place). And then when an actual accident occurs your response is ineffective.
> And then when an actual accident occurs your response is ineffective.
Nothing can be actual human care and attention. Everything can break and no automated system made by careful people is exempt from needing that.
I'm reminded that late into development of a Pixar movie servers crashed, work was lost, and the automated back up system failed. The only thing which saved it was that an artist took a copy of the project home to work on it.
Some articles I found suggest that a trip was 8 hours to get there and back. Another mentioned being in the sub for 12 hours. I'm guessing it's a 4 hour trip each way and then they spend a number of hours checking the wreckage.
The wreckage site is around 370 miles from Newfoundland, Canada.
Seems like the rescue effort could be unfolding over days.
That's how you bring several kW of power down to an ROV.
An umbilical cable, copper conductors and fiber optics inside steel wire sheath. The weight of the thing makes it impossible to attach it directly to the ROV - It would be unmaneuverable - so instead they bring it down to a TMS (Tether Management System) - basically a cage where the steel umbilical terminates and a spool of lightweight tether cable, 100m or so, which the crew then pays out to give the ROV the capability to snoop around at depth.
I went to sleep, time zones being what they are, but see that user jacquesm posted a link to a most impressive rabbit hole of engineering porn.
As an aside, one of the first field jobs I attended after graduating was commissioning some equipment fitted onto the R/V Knorr, the very ship which was used for finding the Titanic.
For a Titanic buff, that was a great experience - doubly so when the project manager at the Woods Hole end found out that I had more than a passing interest in the wreck, and during lunch one day suggested we go see if we could find Bob, as he believed him to be on the premises.
Bob, of course, turned out to be Robert Ballard, who turned out to be an incredibly gentle and patient guy who answered each and every question I had like it was the first time he had it posed to him, despite probably having had them thousands of times before...
I've done some work for a company in this domain, it is incredibly interesting and you could easily lose several lifetimes on all of the engineering details.
Leaving aside the literal tons of weight a tether would require just to life a single person back to the surface (and the weight of the tether), it also could get pushed around a lot by the current. And, most importantly, once you are down there and want to navigate the wreck it would get in the way.
The weight of the tether doesn't matter when it is in water. You just design it to be neutrally buoyant. Either using mini pressure vessels or tanks of light oil.
The compressibility of water is fairly negligible - the density increase is only 1% for every 2 kilometers of depth. And obviously the cable also compresses at depth - probably by a similar percentage,
The metal wires in the tether is heavier than water. This is balanced by twining air/gas hoses into the tether. Gas compresses by 50% for each 10 metres of depth in water, so that's a whole different scale.
You either put floats (ie. Gas chambers of fixed volume) or sealed tanks of a light liquid, for example kerosene.
For high depth like this, tanks of a light liquid are probably most suitable. I'd probably use liquid butane. With a vapour pressure of 40 psi, it is easy to contain, and is has a density of only half of water. If it leaks, there won't be an environmental cleanup cost either.
Reminds me of the story of the first crewed submersible to the bottom of the Mariana Trench. During the descent there was a loud boom, like some something massive broke. After recovering from the shock, they decided to continue the dive, because if it was something important, they would have already been dead.
> At 30,000 ft. a sharp crack rang through the ship, shaking it violently. The water pressure outside was more than 6 tons per sqare inch., and even a slight fracture in the hull would have meant certain death. It proved to be only an outer Plexiglas windowpane which had splintered under the pressure. The inner hull remained watertight. "A pretty hairy, experience," admitted Walsh.
>David Concannon, an adviser to the company, said Oceangate lost contact with the sub Sunday morning. It had a 96-hour oxygen supply, he said in an email to The Associated Press on Monday afternoon. “Now 32 hours since sub left surface,” said Concannon, who said he was supposed to be on the dive but could not go due to another client matter. He said officials are working to get a remotely operated vehicle that can reach a depth of 6,000 meters (about 20,000 feet) to the site as soon as possible.
They went during a brief weather window. One of the people on board had suggested just prior to departing that this was likely to be the only trip the vessel made this season. Rough phrasing in hindsight.
Just like this persian who was given a lot of money to go on the Titanic's maiden voyage, but gave the money to charity instead. He came to the USA in 1912 and spoke out against the racism here
> Throughout his U.S. visit he swept aside the social protocol of segregation by insisting that everywhere he spoke be open to people of all races. Not the biggest crowd pleaser at the time. At the Great Northern Hotel on 57th Street (now the Parker Meridien), the manager vehemently refused to allow any blacks on the property.
> "If the people see that one colored person has entered my hotel, no respectable person will ever set foot in it," he said. So Abdu'l-Baha instead organized a multi-racial feast at the home of one of his followers, with many whites serving blacks -- a subversive, even dangerous notion at the time.
You may end up surprised, its a religion which handles meeting modern world and its values much better than any other major religion (maybe apart from Buddhism, if you consider it religion per se).
Sad to see its cradle, Persia, to go full hatred on it. Interestingly, they found their safe haven in Israel. I hope main reason wasn't to just insult arch enemy, but rather simple tolerance.
The were repeatedly exiled by persian authorities and ultimately sent to a prison city in Israel (Akka), so it wasn't their direct choice they ended up there. I guess the political situation back then was different. Abdul-Baha from the article above was with them, and His father Baha'u'llah as well
That said they would not consider their oppressors as their enemies but rather that the oppressor is hurting themselves more than their victim by depriving themselves of actual happiness
Here is a letter Abdul-Baha's father wrote to the persian Shah while in prison. It is just incredible to say the least
For those mentioning about detailed location tracking / communication: Non-low-bandwidth communication underwater is really difficult due to the physics of EM waves traveling through a medium such as water: https://en.m.wikipedia.org/wiki/Underwater_acoustic_communic...
If you mean "why aren't they using sonar to locate the missing vessel", I'm sure they're trying. One of the articles about this event I saw mentioned a P-8 Poseidon being deployed to assist the search. I would be extremely surprised if at least a few sonobouys hadn't been deployed.
If you're asking why they don't have a acoustic phone for underwater communications, I couldn't tell you.
As I understand the Janus digital underwater communications standard (which as I understand is an open standard and is also standardised as NATO STANAG 4748, so search vessels should be able to understand it) range is about 28km [1], not sure about purely analogue implementations, but some solution should be easily achievable for any entity capable of building the submarine in the first place. Maybe they simply elected not to install one? or maybe the sub is drifting and the search area is too large to reliably establish communications.
They seem to have a "move fast and break things" approach and declined to get their vessel "classed" [2] as they claim to be too innovative to follow industry standards for such things... does not bode well for the missing vessel.
Exactly. Judging from that video their approach to designing and building that thing seeks very amateurish, nonchalant, and lacking an eye for redundancy and safety.
Not an expert...but my impression is that the implosion, at depth, of even the very small submarine in question here would generate an extremely loud "noise". Probably obvious to any hydrophone on the support vessel, and near-certainly recorded in detail by military monitoring systems.
I more or less do that as well, but after each comment, I’m dropped back on the thread that I’m still halfway through. Depending on how I scroll and how the comments are re-ordered (as they’re voted on), I’m subject to crossing sub-threads, especially on mobile and when I’m partly killing time. In this case, I was in an Uber and then an airport so a little more prone to start-stop even within the one article.
That’s an explanation and not really an excuse. This one was sloppy, as I guess they all would be.
"Real-Time Health Monitoring
The most significant innovation is the proprietary real-time hull health monitoring (RTM) system. Titan is the only manned submersible to employ an integrated real-time health monitoring system. Utilizing co-located acoustic sensors and strain gauges throughout the pressure boundary, the RTM system makes it possible to analyze the effects of changing pressure on the vessel as the submersible dives deeper, and accurately assess the integrity of the structure. This onboard health analysis monitoring system provides early warning detection for the pilot with enough time to arrest the descent and safely return to surface."
I am surprised that real time monitoring of the hull is even a consideration, I would have expected it to be designed an built with massive safety margins and then inspected very thoroughly after each trip. The above paragraph seems to indicate that they would monitor hull health during the trip and stop descent if it showed signs of stress. But I am skeptical that they would see signs of stress before it simply imploded at depth.
> "No other submersible currently utilizes real-time monitoring to monitor hull health during a dive. We want to know why. Classed subs are only required to undergo depth validation every three years, whereas our RTM system validates the integrity of the hull on each and every dive." [1]
I suspect your intuition may be why RTM is not really used. Failures happen too quickly for them to give useful preventative data, perhaps?
It sounds a lot like marketing jargon to my ears. Not just the ridiculous name but the vague description- and obvious fact that even if it works it certainly isn’t bailing you out at depths where the craft is most likely to fsil.
I’m surprised those who paid to ride were not more atuned to this.
I don’t want to pick on Honda here, as a long time owner, but the name itself keeps reminding me of “Super Handling All wheel Drive” (SH-AWD)
My thoughts exactly. They should be doing a deep inspection of the hull before and after every dive. RTM sounds good until you have a failure at 10000 ft down and die instantly. “We detected a failu -“ and then you go boom.
It's worth contrasting the design of this vehicle with what is ostensibly the world standard for deep-sea research submersibles, Alvin of Woods Hole Oceanographic Institution.
As a US Navy-owned submersible, Alvin also undergoes extensive safety evaluation under the Naval Sea Systems Command SUBSAFE program: https://ndsf.whoi.edu/its-official/
I think it's 30 days of diving, not 30 continuous days submerged. You can use it a whole month before you need to take a maintenance day.
There's a 3d panorama view of the interior of the sphere linked from the article - I doubt anyone's spending more than a day in there at a go, let alone with someone else.
Edit: apparently, it's 3 people - the pilot and 2 scientists.
They just had a story on this on CBS Sunday Morning. A reporter actually went down in the sub but it got called off mid-dive. He had to go back later. It didn't seem safe.
I believe he also mentioned they were “lost” for a few hours when they lost communication so perhaps all hope is not lost for the people currently on board.
I'm surprised the craft doesn't have a pinger, like airplane black boxes do (and those can survive on the ocean floor, too). 96 hours of oxygen won't help if it takes 200 hours just to find where they are.
The Trieste dive to the bottom of Mariana Trench were able to use voice communications from the sea floor. Should be possible from Titanics depths then, seeing as Mariana’s is 3x deeper. Assuming the sub hasn’t already imploded, that is.
Not a lot of information about this one. Does the Coast Guard have a submersible of their own that they could use to recover, even if they were able to find them?
Yeah, the article is light on details. We don't know if they sank or if they're adrift on the surface somewhere after some failure.
If they experienced an emergency underwater and were not able to surface, I'd fear for the absolute worst.
People can survive in sunken submarines long enough to be rescued, but those are typically large submarines with multiple rooms that they can seal themselves off in. I doubt a tourist submarine, or really any submarine going to this depth, has multiple compartments. Many military submarines have a test depth of around ~1,500ft or less & a crush depth of around ~2,500ft or less. Titanic sits at 12,500ft. It takes specialized subs to get to this depth, and they're typically very small, one cramped compartment, vessels.
Even if they sank but did not suffer a leak, it's unlikely there would an air supply long enough to support a rescue.
If they sank, a rescue seems very unlikely. Nonetheless, I hope for the best.
There is a small toilet located in Titan’s front dome – it doubles as the best seat in the house. When the toilet is in use, we install a privacy curtain between the dome and the main compartment and turn the music up loud."
If the sub was designed like a few other deep-sea craft I've looked at, they'd have positive buoyancy and weights to overcome this; the idea being that having to blow ballast tanks at 400 bar pressure differential is rather inconvenient and failure prone.
Instead, the weights (attached with electromagnets) are simply jettisoned when it is time to recover to the surface and off you go. The upside to such a simple system, of course, is that it is exceedingly reliable and fail safe.
Provided you do not suffer a hull implosion, of course.
"Pogue also shows the vessel uses construction pipes as ballast."
I'm having trouble finding the interview video, but dropping ballast involves the crew and passengers rocking the vessel to drop the pipes off the side.
Interesting. If they were resting on the bottom. Could you even rock hard enough to drop the ballasts? Although even if they can get to the surface if they have now power how the hell do you find them? It's not like they'll be float on the surface they'd likely be just below the surface.
Apparently most "narco submarines" are spotted visually from the air, and those are camouflaged to blend in with the ocean and produce minimal wake, so I would imagine spotting the missing (non-camouflaged) sub at barely-submerged depth would be trivial (as long as it hasn't drifted to far from the last known position) [1]. I saw one of the news articles about this event mention there is a P-8 Poseidon sub-hunting aircraft assisting the search effort, and I would imagine it has a very nice set of optical sensors, thermal cameras, sonobouys, etc. and would have no issues finding the missing sub if it were near surface level ... I don't believe the P-8 has magnetic field sensors but I believe older sub-hunting aircraft had them, which could also be a means of locating the sub.
Unfortunately (and I hope I am wrong) I suspect the vessel is drifting in deep water or stuck on the sea floor - if it were shallow they'd have probably found it already.
I’m afraid not, but other companies could be contracted.
Regardless, for a sub like this to just go missing, likely means something catastrophic happened. At those pressures, the individuals likely died instantly and felt no pain.
Unfortunately from everything I know about submarine disasters there is very little hope of anyone surviving. Failures are often catastrophic and even without that the time to deploy recovery vessels measures in days. Rip.
The US Navy SRDRS is incapable of reaching that depth. There was no point in designing it to go any deeper than the crush depth of manned military submarines.
I don't understand after all these years why there's still this obsession with the Titanic. What keeps fueling its enduring fascination? People spending 1/4 million just to barely see a sunken ship? Bragging rights for the rich?
Costs about $250k per person - https://oceangateexpeditions.com/tour/titanic-expedition/ (Site looks to be down at the moment, probably overloaded due to people searching after this news). I don't think it's particularly crowded, but certainly could become one day in theory.
Yeah I suppose that would be the ideal outcome. I was thinking of some kind of depressurization scenarios where they get crushed by 300 atmospheres worth of pressure.
We'd have to look at the details of the contract to see if half of the ticket price is refunded in the event that they bring you to the Titanic but don't bring you back to the surface.
"Goliath Awaits is a 1981 American made-for-television action adventure science fiction thriller... about an ocean liner sunk by a German U-boat in 1939 whose wreck is discovered in 1981, with over 300 survivors and their descendants living in an air bubble inside the ship."[1]
Watched it as a kid, and it definitely stuck in my head. Quite impressive cast.
You're right, Google showed $125k from other articles and some looking at this earlier (a year or so ago) and $125k sounded right. I guess they doubled it!
> Did it not occur to anyone that it might be a bad idea?
Of course the danger was considered, be realistic and stop letting class conflict cloud your judgement. Something being judged to be dangerous doesn't mean people won't do it, and people doing something dangerous doesn't mean they didn't consider the risks. People go skiing, base jumping down cliffs with wingsuits, cave diving and swimming with sharks. It's okay to do dangerous things if you know and accept the risks.
All of the things you mentioned are activities for the wealthy. Why does that matter? Because having a lot of money can make risk not as risky. Rich people know they will be rescued. They have insurance and fancy doctors. They can afford to be airlifted out of exotic places.
While it's not a conclusive link, it seems to me that people with a smaller financial safety net might not be as interested in such activities because they cannot stand the risk.
> All of the things you mentioned are activities for the wealthy
That's really the key aspect of this story for you isn't it? Screw them because they're rich; I get that, but just own it.
And for the record, you don't need to be rich to go skiing and break your neck on a tree. A whole lot of working class people save up money for a vacation then go skiing. A whole lot of working class people save up money for a once-in-a-lifetime trip to Hawaii and go scuba diving. If you find it hard to believe either of those scenarios then believe this: a whole lot of working class people buy motorcycles and drive them fast. Hell, when I was a teen I used to pedal my $100 bicycle down steep hills as fast as I could. Taking risks for thrills is something that's broadly accessible to just about anybody.
Having been linked this elsewhere in the thread I don't quite like the fact that they're so brazen that they bought internal lighting from Camping World and drive it with a Logitech USB gamepad and using half-ass construction piping as a ballast.
Or the fact that they scrubbed a Titanic launch for the media due to weather (presenting from some kind of briefing room where they presented from a laptop on top of a Breville cooker box), went elsewhere, then scrubbed THAT launch while in the water because the launch platform floats detached...
As opposed to the professionals who went with a microsoft xbox controller? [1]
> Or the fact that they scrubbed a Titanic launch for the media due to weather
Yes? Weather is a thing. This is not a ride at disney land, of course they cancel the operation when the circumstances are not favorable. In fact doing the opposite would be foolish.
The company in question might be full of jokers, but your points don’t quite illistrate this well. They are about appearances and not substance.
> As opposed to the professionals who went with a microsoft xbox controller?
I think what's more telling is that they didn't even splurge on the actual Microsoft Xbox controller. They cheaped out with an unproven logitech gamepad. When you're already doing something in an unorthodox way at least don't half-ass it.
> The company in question might be full of jokers, but your points don’t quite illistrate this well. They are about appearances and not substance.
Your distinction is a bit arbitrary. Every point about this company will always be about appearances unless you have first-hand accounts or experiences. Otherwise, info on the company's technology, choices, strategies or anything else will always be based on appearance. In the absence of more concrete evidence, these small indicators can at least provide something to infer from.
> Your distinction is a bit arbitrary. Every point about this company will always be about appearances unless you have first-hand accounts or experiences.
Not really. Here is a substance based argument: there is no underwater FAA. This company, and any other private submarine company is setting their own quality level and then marking their own homework to see if they have met it. In a commercial environment they are incentivised to cut corners and there is no external force resisting this.
Then you can ask them about their tech and procedures. Do they have redundant means of communication? Do they have multiply redundant means to release the ballast? How many hull penetrations there are and how are they implemented? If they are unwilling to discuss these questions that is worse than a bad answer.
Some comments are criticising their choice of carbon fiber for the middle section of their pressure vessel. I don’t know enough about the engineering there to decide for myself if that criticism is fair or not but that is an argument about substance not appearance.
I think this is the big thing for me. David Pogue, when he went on a dive with them last year, pointed out that the vessel has no beacon [1]; yet the door bolts from the outside. Apparently there was a five-hour period where the company did not know the location of the sub after it resurfaced.
To me, that seems crazy. Having a GPS beacon seems like a no-brainer for safety purposes. It feels indicative of the engineering as a whole.
>In a commercial environment they are incentivised to cut corners and there is no external force resisting this
Please if you are incentivized to cut $10 on the main control interface of your expensive sub that also is to drive your business, you have some fundamental cultural problems beyond "commercial environment".
>In a commercial environment they are incentivised to cut corners and there is no external force resisting this
Please if you are incentivized to cut $10 on the main control interface of your expensive sub that is incredibly low volume production, you have some fundamental cultural problems and its not a business decision.
Can’t you say the same thing about the logitech one? My point is that using an off the shelf solution is not necessarily a bad one. Probably there are differences between the reliability of the different controllers within that category but not to the level where choosing one over the other is a clear sign of engineering mallpractice.
There are far more Xbox controllers in use than Logitech. In the gaming community, the Logitech controllers are known to be janky and less reliable.
The PlayStation controllers are more popular globally, but have not had a great track record when it comes to operation with anything but a PlayStation.
I get what you're saying, though, and I'm not faulting them for using an off-the-shelf product. I'm faulting them for using a substandard product.
I think you have unreasonable expectations. Off-the-shelf components may be more reliable than custom developed products (especially since you can afford a backup or two).
Also, with respect to emergency ballast - cheapness is a virtue. You're supposed to drop it in an emergency, and hesitating because "I don't want to lose my expensive weights" could kill you. This is a consideration for recreational scuba too, instructors recommend buying cheap weight belts (and the companies selling expensive ones usually advertise "free replacement if you use them in an emergency").
Yeah. I'm not sure having Boeing design and build me a $10,000 LED lighting array is necessarily a big improvement and, if you're worried about the reliability of your game controller? Buy two maybe of everything maybe, even three? There can be reasons to use expensive bespoke coffee pots on commercial flights. But going with the gold-plated aerospace version isn't always the answer.
Though choice is still important, why that gamepad? Especially if it was the wireless version.
Building the controls with wired arcade buttons and an arcade joystick would be a little pricier but you'd get parts designed to take a beating, plenty of real world usage to demonstrate this and no potentially flaky usb/wireless stack that you have no control over to deal with.
I could take some guesses. It's cramped with a lot of people; wires invite tangles or damage if someone accidentally yanks on it. Especially if you want to operate the vehicle from both sides of the interior.
Those controllers have millions of hours of playtesting by people that are sensitive to the slightest twitch. I'd trust them more than most automotive components.
I'm more curious to know how they run the control lines. A thruhull at 400 atmospheres must be something special. Or maybe it's wireless to the machinery outside? But the carbon fibre and titanium enclosure would be a problem.
I would not actually trust them more than an automotive component, I think most accelerator pedals use Hall Effect sensors (usually two of them in the good designs) that are much less likely to wear out and cause spurious inputs or failure than the basic potentiometers on a game console, especially a very cheap one. Get an X-box controller at least, and have a couple spares wired in, in case the wireless one fails.
Does a submersible like this only drop ballast weight in an emergency, or every time they’re ready to go home? I know submarines tend to use diving planes and pneumatic ballast tanks (flood with water, or inject air to push water out), but I don’t know if that’s an option down at 400 atm.
I heard an interview this afternoon on NPR with David Pogue (the bbc guy who filmed a ride). He said there are 7 different ways of surfacing, including several that do not require electricity and don't even require consciousness. For example, some of the ballast is attached by mounts that dissolve after a certain number of hours in water (presumably less than 96).
Thanks for posting that link. However, I came to the opposite conclusion - I was rather impressed. I respect someone who is prepared to make a financial loss whilst breaking new ground technically more than someone who's trying to cut corners on something conventional. (Assuming of course that Stockton Rush is telling the truth about losing money, of course.)
It may be crass, but it's also true. Contrary to what many folks say, this is the exact time to be talking about these deficiencies. Putting it off to later, is simply an attempt to memory hole them.
The company lost a submersible for four hours on a previous dive. They don't talk about that. In fact, they killed the internet so the reporter that happened to be onboard couldn't report it. (That's what we call, a "cover up".) Putting much weight into a company declaring their commitment to safety is a bit of a fool's errand. Even the most reckless company says that safety is paramount.
Isn't visiting places filled with dead and decomposing people a fairly normal tourist activity? Various catacombs, graveyards, temples, battlefields, memorials, Pompeii...
I've got no real thoughts on the "stupidity" of doing this, but visiting the wreck of a famous ship doesn't seem an obviously unsympathetic thing to do compared to visiting the ruins of a city.
Even in the ocean, human remains may be partially preserved if the conditions are right for it. They found human remains in or around the Vasa, a Swedish warship that sank in 1628. Mostly just bones, but also a little bit of soft tissue more than 300 years later.
> Organic materials fared better in the anaerobic conditions, and so wood, cloth and leather are often in very good condition, but objects exposed to the currents were eroded by the sediment in the water, so that some are barely recognizable.[43] Objects which fell off the hull into the mud after the nails corroded through were well protected, so that many of the sculptures still retain areas of paint and gilding. Of the human remains, most of the soft tissue was consumed, leaving only the bones, which were often held together only by clothing, although in one case, hair, nails and brain tissue survived.[44]
Yes...but those are places where where the dead received "proper" burials. (Excepting Pompeii, and maybe some battlefields. Pompeii tends to get a pass because "ancient", "technically buried", and "A-listed Roman cultural site".)
And generally, visiting ~none of those other places is a brag-worthy way to show off being one of the modern 0.1%. (Which, these days, gets very little sympathy in many quarters. Even without the "vultures draped in diamonds" aspect here.)
It's very common for recreational divers to visit ships with bodies still in them. Maybe it's morbid, but it's common and generally you don't need to be "0.1%" to do it. If this story were about some working class people who died while scuba diving around a wreck in shallow water, would you still be trying to vilify them for it?
I'm trying to explain the sentiments which user paganel originally voiced - which I suspect are kinda common. My sense is that the strong negative feeling are tied to how much of a "just too many emotional points against it" corner case this is. A famous & famously tragic shipwreck, the dangers inherent in their extreme tourism, how very few people can imagine "it coulda been someone like me in that little sub", the "mass grave" scale of death, the kinda-mythical "forbidden underworld" aura to the site, etc., etc.
I think some of the pushback that I feel to that is that it seems like a socially acceptable guise for just wanting to hate rich people. I'm fine if your opinion is "screw rich people who spend this much on weird things", or even "Rich people who died doing something this frivolous deserved it." But just own that.
If this had been the original diving expedition to the Titanic to find the wreck for the first time, or even the followups, and people had potentially died then, I doubt we would have had this many people out in the comments about how its distasteful and they're hoping it would dissuade anyone from doing it again.
At least "I hate rich people" is a consistent view whether you agree or not. Trying to make that view more socially acceptable by adding new and inconsistent layers on top about how visiting a place people died is inherently something that makes them unsympathetic just feels weird.
> I think some...socially acceptable guise for just wanting to hate rich people.
Yes, some. But my feel is that if a similar number of even-richer people had (say) died in the crash of a luxury helicopter ferrying them to Everest Base Camp, then the negative reaction would have been far less notable.
Yes, it’s a combination of hating the rich people (which is a very valid sentiment, btw) and of invading a sacred “burial” space. If they had somehow gotten there on their own dime, like those divers you mentioned, then, yeah, it’s a little too morbid for me but whatever suits them.
But to sell tickets (worth a staggering 250k) in order to visit the burial place of a couple thousand people is just not ok, it destroys the place’s sacred aura.
Just imagine if they had left the ruins of the Twin Towers in place, including the dead and decomposing people under those ruins, and if they had started selling tickets in order to visit said place. Totally not ok.
Oh sure. I'm not arguing this is a good idea or not a way to show off your money, just that it's kinda a weird assertion that visiting a place where people died and weren't properly buried at some point in the past is uniquely distasteful.
It's not as if they're going to look at the dead bodies, and as someone else points out, there's almost no chance there's intact remains left at that depth after all this time. There's plenty of less-deep shipwrecks all over the Caribbean or other coastal areas where people probably died that are normal enough to scuba dive into and I'm not sure people think that that's distasteful.
The "you spent how much on this" part is something I'm absolutely fine with people taking issue with, but it doesn't seem that much more gauche than flying to space or just flying your private jet around.
Also crass, but the eat-the-rich crowd might applaud the concept of finding more people willing to pay $250k for a thrill ride and imploding the vehicle at the bottom of the ocean or in space.
OceanGate: "We use military grade equipment! It's risk-free"
Billionaire: "Sign me up"
Jokes aside, I wonder if billionaires do assess more thoroughly the risks than any normal person. They can easily dedicate a team to assess the risks to their various activities.
I don't know any, but my guess is that multimillionaires and billionaires asses risk much like most normal people. This isn't like a business venture or medical treatment where you can put a team together to assess the risk for you. It's more like skiing or scuba diving where there is some inherent risk and you decide to do it or not.
Based on their results from helicopters, I’d say they have a higher risk tolerance than many would be comfortable with. Helos seem to me to border on being a natural predator of billionaires.
Rush also said during the interview, "You know, at some point, safety just is pure waste. I mean, if you just want to be safe, don’t get out of bed."
"Don’t get in your car. Don’t do anything," he added. "At some point, you’re going to take some risk, and it really is a risk/reward question. I think I can do this just as safely by breaking the rules."[0]
I don't think it's stupid to expect that submersibles are well-engineered.
I'd also imagine that the tourists trusted the reputation of the operator. Both the state of the equipment and that their safety checks and processes were stringent. Especially since they claimed to aid in the science.
There aren't many priors for civilian submarine disasters.
I'm not sure there's any particular reason to think that this is an extraordinarily dangerous activity relative to things like mountain climbing--even on many less extreme peaks.
I don't see any reason to think why it isn't. Unless you don't have a basic understanding about the most primitive laws of physics. Even the slightest mishap at that depth and you're in more trouble than you would be if you were stranded on the ISS.
Some mountains like K2 have an extremely high kill rate and it still happens almost every year. Probably higher killing rate than all the Titanic exploration missions that did not explode in the past. It's not so much about physics but just looking at probability
I'm sure they do. But the chances of dying on board of an experimental submarine which is subjected to absolutely insane pressures are probably quite a bit higher still than the chances of dying on K2. But whether it's higher than the Titanic exploration missions is not the same as the manned Titanic missions of which there have only been very few.
Those things work right up to the moment that they do not, this stuff is at the cutting edge of technology and tourists simply have absolutely no place there. The only reason those rich folks tend to do stuff like this is because they like to brag about such stuff, not because they're interested in the science behind it (if they were they likely wouldn't go). The Titanic is less accessible than space.
More Darwin award candidates then. I fully support them in their choices but I find the fascination with such endeavors hard to understand. If it is a first then I get it, that's exploration and somewhat interesting. But if it is just for kicks or bragging rights then I don't get it. To me the risks don't outweigh the benefits.
You don't even need the Everests and the K2s. I won't characterize things I've done in the 6000m range or even just peaks with tricky rock sections as dangerous per se (or I probably wouldn't have done them) but people do develop serious altitude-related conditions, avalanches happen, and people just mis-step.
The particular reason is “450 atmospheres of water pressure.” This is a lot. You don’t have this type of threat to the structural integrity of your gear at Everest, etc.
It is not. The article mentions that the submarine is bolted from the outside so that even if they surface, they can’t open it from the inside. This is in the history of bad designs, the worst. We have “doors must be unlocked when the building is occupied” signs all over the country, yet, no one thought a safety hatch the can be opened from the inside in emergencies could be useful?
> no one thought a safety hatch the can be opened from the inside in emergencies could be useful?
It’s quite possible that they considered it and felt that it would compromise the structural integrity and the risk would be higher than not having it.
Yes, very much so. There are very few of them made and most of them are ROVs not manned for very good reasons. https://en.wikipedia.org/wiki/Deep-submergence_vehicle lists about 30 of them (manned ones, there are far more ROVs), each and every one of these should be considered experimental. Typical uses are scientific exploration and navy. Tourism is definitely not a main driver behind their development.
Nuclear submarines can maintain a safe atmosphere internally with electrolytic cells and special candles, working with the wider gas management system.
The sentence with company name was added later, I still have the browser tab open when it was submitted to HN. It used to say "Multi day trips to the wreck cost tens of thousands of dollars and one dive to Titanic." Now it mentions the company and more accurate pricing.
Makes me wish for an extension that would temporarily - for a few days or weeks - cache everything you see under a given URL[0], and 1) tell you if the content changed since your last visit, 2) allow you to browse history of versions, and, importantly, 3) diff entries in that history.
Plenty of times I had a vague hunch the page said something slightly or perhaps entirely different just minutes or hours earlier, but have no easy way of checking it. Even if I have it opened in another tab, most likely the browser already decided to unload the content and reloads the page when I try to view it.
Bonus points if it could sync across devices - e.g. between phone and desktop using Firefox sync. Even recently, I had a situation where I was convinced someone edited their HN comment to say something 180° opposite to what it said earlier, in the 30 minutes between me reading it on a phone, and then reading it on a desktop later. Of course, the phone tab unloaded itself long ago, so I have no way of checking if it indeed happened, or was it just my brain misreading it the first time...
--
[0] - +/- ignoring or employing some workarounds for SPAs that don't update URLs when the page content changes, or don't even use URLs to locate content in the first place.
I wouldn’t say they’re relying on it for operations. It’s not like they doing some internet controlled submersible, it is still watercraft with someone at the helm and more than likely, they use some type of local communication for the surface crew to communicate with the expedition crew.
Likewise for me. However, I'm on land, where the Starlink satellites don't have to relay comms between each other. It's a completely different story out in the middle of the ocean. Starlink only recently started their laser-based relay system, and I have not heard reports about its reliability. It might work great, I don't know. I do know that it was a difficult engineering problem to solve.
I'm speculating, but I'm fairly sure that they already have any and every satellite communication system available on-board, just as a back-up. If they're using Star link, it should be because it's working best.
It's intriguing to see what kind of personality a billionaire has that pushes him to do these stunts and also publicly brag about them. I hope it's not a necessary ingredient to success as I do not intend to live like that.
That being said,
> He added that because the passengers were sealed inside the vessel by bolts applied from the outside, "There's no way to escape, even if you rise to the surface by yourself. You cannot get out of the sub without a crew on the outside letting you out."
How come there's no way to communicate once under water? Wouldn't be possible to launch a tiny probe attached to the exterior of the sub, either manually or automatically when in trouble, sort of a black box, that bounces back to the surface to broadcast crew messages, sub data and location? Seems like an obvious safety device to have. Are there any technical reasons why this is not available on a vehicle with suck poor performance?
Probably the communication devices were blown off by the shockwave in the case of an implosion. It’s absolutely possible to have communications with the surface at this level; Trieste from the bottom of Mariana Trench was able to communicate back up to surface. That was 3x deeper and the early 60s.
> Contacted by CBS News, the Canadian Coast Guard said the rescue operation was being managed by the Boston Regional Coordination Center, and a map showing jurisdictions for the various coastal search and rescue agencies off the North American coast shows the location of the Titanic wreck within the Boston center's area of responsibility.
The search and rescue jurisdiction map is fascinating, although some of those areas are so huge that I wonder how much it really means in practice. If you're lost off the coast of Ecuador, are you really supposed to call the San Francisco Coast Guard?
It generally doesn't matter who you call. The call and rescue efforts will be directed through the designated control centre.
This kind of rescue redirect is especially common now with the advent of EPIRBs (Emergency Position-Indicating Radio Beacons) which are registered to a particular country/authority, but work anywhere in the world. If your Lisbon-registered is activated far enough off the coast of Ecuador to be in the SF zone (and assuming the map is correct), the ARCC Lisboa will contact the SF MRCC and they'll co-ordinate the rescue effort.
There are some very strange areas on that map. Check out the large swathe of the East China Sea near China, the Koreas, and Taiwan, the responsibility of Russian search and rescue in Vladivostok.
After hearing about the experimental nature of the firm (see: https://www.youtube.com/watch?v=29co_Hksk6o&t=203s), does anyone have any perspective on the firm's ethics or responsibilities for unknown dangers? How does this compare to say astronauts or experimental aircraft pilots?
Seems like they’re going to get sued if the passengers and crew aren’t saved. Possibly even if they are saved. Maybe the contract they get people to sign is tight enough, but everything I’ve read so far seems like they were a bit reckless. They don’t have to inspect their hull for issues every dive; they have real time monitoring of the health at all times! We just pop them back up when we discover an issue…
But what if that issue is detected at a depth at which nothing can be done? At a depth where death is imminent no matter what? The thing is held together with RV lights and a crappy Logitech controller from Amazon. What else have they elected to skimp on?
The “why Titan isn’t classed” page is hilarious too. They mention of the 25 pre checks they have, the majority are for surface operations, not underwater operations. Does not give one confidence and reads like a joke after this debacle.
As far as I can tell I think the company involved hasn't released a passenger list.
edit: An earlier version of the BBC's article said it wasn't known if people were on it at all; clearly there were, but I'd bet this is why the headline is so unclear.
I see. Regardless it sounds like it was unmanned because of the deëmphasis on the missing passengers. It's like saying “missing car” when people that were in a car go missing.
I get the flex this affords, but I can't think of anything less appealing than spending 8 days underwater in a tiny capsule. I hope they're found and nothing happened.
I was confused by the article as well. I believe it's eight days in total including the trip on the ship to get there and back. And then the actual dive is around 8 hours.
So much skimming here eh. The whole trip can take 8 days, from launching on a ship to take you out to sea. The actual dive itself is supposed to be 12 hrs from “bolts on” pre dive to “bolts off” getting out of the sub. 8 hrs underwater, not 8 days.
The fibers are strong in both tension and compression (not equally so, see figure 1: http://home.iitk.ac.in/~mohite/axial_compressive.pdf), but in compression their aspect ratio is very very very large so they buckle instantly… unless you glue them together so each strand is supporting the ones near it and the effective aspect ratio is much less. Aside from fiber wound pressure bottles just about any real world composite structure will experience bending forces which will put the top in compression and the bottom in tension. The designer might need to reinforce the compressive side more, depending on the application (e.g. if designing for stiffness the strength might end up with considerable margin for both tension and compression).
Probably not pressurized much in the scale of things.
Humans are incompatible with nearly every gas at 13000feet/400 atm and beyond. Nobody has done it.
Cabin pressurization might get you to ~50atm, but that's around the extreme limit, so regardless of cabin pressurization the hull has to handle most of it.
Here's hoping it has and they can be found quickly.
With a pressure differential of 399 atmospheres I don't think that the vessel being pressurized is going to be much of a factor. It might as well be vacuum.
TBH at this stage we just don't know. They might not have imploded but instead been left stranded on the bottom with an intact pressure hull but some other sort of equipment failure. Still a hopeless situation unfortunately.
"OceanGate will take advantage of lessons learned during the construction of its carbon-hulled Titan submersible, which was originally built for Titanic journeys. Rush said tests that were conducted at the Deep Ocean Test Facility in Annapolis, Md., revealed that the Titan’s hull “showed signs of cyclic fatigue.” As a result, the hull’s depth rating was reduced to 3,000 meters.
“Not enough to get to the Titanic,” Rush said."
Source: https://www.geekwire.com/2020/oceangate-raises-18m-build-big...